docs: def _filter_matrix_rows(cls, matrix):
          '''matrix = output from _to_matrix'''
          indexes_to_keep = []
  
          for i in range(len(matrix)):
              keep_row = False
              for element in matrix[i]:
                  if element not in {'NA', 'no'}:
                      keep_row = True
                      break
              if keep_row:
                  indexes_to_keep.append(i)
  
          return [matrix[i] for i in indexes_to_keep]